Safe and effective drug therapy by injection depends not only upon accurate diagnosis, but also on efficient and reliable introduction of the medical substance into the subcutaneous cellular tissue without introducing contaminants or ambient air. The applicable drug or pharmaceutical must first be drawn from the resident container or vial into a syringe before injection. The integrity and features of the vial, therefore, are influential over the overall safety of the injection.
Typically, great care must be taken when a needle cannula of a syringe is used in conjunction with a vial containing a pharmaceutical to be administered to the patient. As the pharmaceutical is drawn out of the container via the needle cannula, precautions must be taken to avoid air being drawn into the syringe. In rigid vials, air must be introduced into the container to fill the void created as the liquid pharmaceutical is withdrawn. This volume of air then becomes susceptible to being mixed with the pharmaceutical or being drawn in through the needle cannula and creating air pockets in the syringe barrel. Catastrophic consequences could result if these air pockets are subsequently injected into the patient along with the liquid pharmaceutical. Also, drawing ambient air into the vial can introduce airborne contaminants to the pharmaceutical.
Some patients, or their parents or guardians, must administer pharmaceuticals on a regular basis. Some medications are very expensive and are also very critical as to dose. Therefore, it is important that the amount of the medication aspirated into the syringe for each dose be precise. Since the person administering the pharmaceutical may not be medically trained, obtaining accurate, consistent injections is often difficult.